In the conventional art, in production of disposable underpants, disposable diapers, or the like, a web cutting device is employed that, after cutting a web, conveys individual cut pieces and changes the orientations of the individual pieces during the conveyance.
An example of such a web cutting device is shown, for example, in FIGS. 11 to 15. FIG. 12 is a schematic perspective view showing the state of carrying a web. As shown in FIG. 12, a web W is conveyed along the cylindrical outer peripheral surface of a stationary drum indicated by a dashed dotted line, in the circumferential direction indicated by an arrow D1 and then the web W is cut. Then, individual pieces W2 obtained by cutting are conveyed with changing the orientation, and then transferred to a subsequent device at a delivery position SP.
FIG. 11 is a schematic diagram showing the configuration of a web cutting device. FIG. 15 is a sectional diagram showing the configuration of a web cutting device. As shown in FIGS. 11 and 15, a plurality of travel members 113 are held in a freely movable manner along the outer peripheral surface of a stationary drum 150. Anvils A1, A2, . . . , Ai, . . . , An moving together with the travel members 113 are arranged between the travel members 113 adjacent to each other.
Each travel member 113 supports in a revolvable manner a shaft member 114 whose center axis r extends in a radial direction of the stationary drum 150. In the shaft member 114, a pad P1, P2, . . . , Pi, . . . , Pn for vacuum-holding the web W is fixed to one end on the radial-directional outer side of the stationary drum 150. Further, a cam follower 115 for engaging with a cam groove 151 formed in the outer peripheral surface of the stationary drum 150 is formed at the other end on the radial-directional center side of the stationary drum 150. In the travel member 113, a groove member 121b for engaging with a protruding part 121a fixed to the stationary drum 150 is fixed and then the protruding part 121a and the groove member 121b constitute a guiding part 121 for guiding the travel member 113. Then, the travel member 113 is held in a freely movable manner along the outer peripheral surface of the stationary drum 150.
The travel member 113 is linked through links 111 and 112 to a revolving body 120 and moves along the outer peripheral surface of the stationary drum 150 in association with revolution of the revolving body 120. At that time, the cam follower 115 formed at the other end of the shaft member 114 supported in a rotatable manner by the travel member 113 engages with the cam groove 151 formed in the outer peripheral surface of the stationary drum 150. Thus, the shaft member 114 reciprocally rotates about the center axis r within a range of 90°. By virtue of this, as shown in a developed view of FIG. 13, the orientations of pads P1, P2, . . . , Pn vary within a range of 90° between a parallel direction and a perpendicular direction relative to the moving direction indicated by a dashed dotted line, that is, the circumferential direction of the stationary drum.
FIGS. 14(a) and 14(b) are main part enlarged views at the time of web cutting. As shown in FIGS. 13, 14(a), and 14(b), the web W is conveyed from a receiving position RP toward a cutting position CP in the direction of arrow D1. A cutting unit 130 is arranged such as to face the cutting position CP. In the cutting unit 130, a cutter 131 is fixed to a revolving member 132. The revolving member 132 revolves in the direction of arrow D2 in synchronization with conveyance of the web W. As shown in FIG. 14(b), in the web W, when a portion extending between the two pads Pn and P1 passes the cutting position CP, the portion is pinched between the tip surface As of the anvil A1 and the blade edge of the cutter 131 so as to be cut.
As shown in FIG. 15, the center axis X1 of the stationary drum 150 and the center axis X2 of the revolving body 120 are distant from each other. The anvils A1, A2, . . . , An are held in a freely movable manner along a cylindrical surface coaxial to the center axis X2 of the revolving body 120 and then, as shown in FIG. 11, at the delivery position SP, retract from the conveyance path for the web moved and held by the pad Pi (for example, see Patent Document 1).